Influence of Technological and Environmental Factors on the Major Ion Composition in Cooling Water Discharges of a Nuclear Power Plant

ABSTRACT Water is extensively used for cooling in power plants, accumulating major ions (HCO₃⁻, CO₃²⁻, SO₄²⁻, Cl⁻, Ca²⁺, Mg²⁺, Na⁺, and K⁺) in the cooling water system. This study quantitatively examines the factors influencing the composition of these ions in the cooling water cycle and assesses their environmental impact upon discharge into the Styr River (Ukraine). Over a 5‐year monitoring period (2018–2022), ion concentrations were measured in process water and receiving surface water using certified laboratory methods. The findings reveal that sulphate concentrations ranged from 17.3 to 375 mg/L, chloride from 9.3 to 90.0 mg/L, and total dissolved solids from 230 to 1035 mg/L, with seasonal fluctuations observed. Statistical regression models were developed to predict post‐discharge ion concentrations based on intake water quality and cooling system operational parameters, demonstrating a strong correlation (coefficients of determination R‐sq = 82.4%–98.8%). The study uniquely integrates the grey water footprint (GWF) methodology to quantify the required dilution volumes for maintaining regulatory water quality. The results indicate that while ion concentrations increase in return water, they remain within permissible limits, ensuring no significant ecological disturbance.